I recommend Foxit for the reading and viewing of PDF files and love it.
Regarding cleaning your own drive.
You are comfortable enough with computers to seek help online and that puts you way above the normal user.
Question: if you don't mind losing four hours of your life and sharpening your windows reinstall skills cleaning or even better wiping your drive is great housekeeping step but it will consume more time than you initially imagine once you get into the whole why can't I watch DVD's anymore, where did all my files go stuff.
If you do decide to wipe your drive then at least do the following:
*Identify the hardware you have in your machine. Check the mfg's website for a list of the hardware installed.
*Download ALL the drivers you're going to need but make real sure you at least get the following:
2) Modem (if your dial up)
3) NIC (network card) if your highspeed cable/dsl
4) USB drivers (if you use the usb cable for your modem to pc connection)
5) Video or VGA driver (so you can see your computer in its full glory)
*Buy or test drive a disk immaging application that is easy to use. (drivesnapshot, ghost?, etc.)
*Collect all your application media (install keys especially).
*Get a linux live cd to get online help if your bork your windows reinstall. (knoppix, ubuntu, etc)
Don't spend a load of cash on paying some kid at best buy to clean your machine. It's really a waste of money.
Buy a good computer book and figure it out youself and save 100 bucks or so.